Improved strut supported turbine blade



D. v. FOSTER 2,894,719

l IMPRovED sTRuT sUPPoRTED TURBINE BLADE Filed Feb. 21, 1956 July 14,1959 United ares Pate@ t MPRGVED STRUT SUPPORTED TURBINE BLADE DouglasV. Foster, Kansas City, M0., assign'or, by mesne assignments, to theUnited States of America as represented by the Secretary of the NavyApplication February 21, 1956, Serial No. 567,040

2 Claims. (Cl. 253-3915) The present invention relates to improvedcooling means for turbines and turbine blading.

It is an object of this invention to provide improved cooling means forturbine struts whereby the cooled air is kept at a It is -a furtherobject of this invention to provide a specific construction of coolingmeans for turbines thereby reducing ya portion of the high precisionmachining and assembly ordinarily necessary in the manufacture ofturbine blading.

It is an additional object of this invention to provide cooling meansfor a turbine wherein the amount of cooling air used is reduced but onthe other hand the cooled area is increased.

These and other objects will be readily apparent to those skilled in theart from a reading of the following specification and yan examination ofthe attached drawings, wherein:

Figure 1 is lan isometric view of the present design of blading,

Figure 2 is an isometric view iof the proposed blading of the instantinvention, and

Figure 3 in an enlarged view -along section line 3--3 of Figure 1.

vFigure 4 is an enlarged view along section line 4 4 of Figure 2.

In conventional turbine design, cooling means for the turbine is anecessity because of the large increase of the maximum cycletemperature. However, the cooling air is desired to -be maintained `at aminimum as a result of two reasons:

(a) The thrust is reduced approximately in proportion -to the amount ofcooling air used, and

(b) At high ight speeds of aircraft, refrigeration of the cooling air isnecessary; consequently, the less cooling air required, the lessrefrigeration apparatus required and Iit naturally follows the less itwill weigh.

In one form of cooling system used in the cooling of turbine blades andstruts, as shown in Figures 1 and 3, the blade 1 consists of a centraltubular strut 3 enveloped by a non-load carrying sheath 2. The sheath isattached to the central tubular strut by means of webs 5; ns 4 aremounted on the central tubular strut between each pair of webs andbetwix-t the strut and shroud. Cooling air is passed through the bladein any conventional manner thus cooling both the strut and the shroud.The cooling of the strut is augmented by the use of the cooling ns as iswell known.

There are many means for supplying the cooled fluid, as for example, byhaving the uid pass through a refrigerator 6, and pump 7. It is ofcourse understood that numerous other means are Well known in the art.

In the present invention, as shown Iin Figures 2 and 4, the blade 10consists of a central tubular load supporting strut 13 and an envelopingshroud 12 attached to the strut by means of webs or tins 15. Located inthe spaces 18 created by the strut, shroud and each pair of webs is awall 16 parallel to the strut and shroud and spaced from both of them bymeans of the cooling fins 14 secured to the strut. It is thus seen thatwith the above construction, a plurality of U-shaped members are formedwith their bases 19 parallel to the strut so that cooling pockets orbights 17 are created adjacent the strut.

Cooling air is pumped through the cooling pockets or bights 17 adjacentfins 14 and betwixt wall 16 and the strut; the strut is -thereby cooledand the cooling action is augmented by the cooling action of the fins14.

It is evident from the present construction that the amount of thecooling air ow is reduced in view of removal of the cooling action onthe outer shroud; the amount of the cooling air is further reduced bythe increased cooling `iin area for a given shell supporting iinpitching.

It is also seen that by the use of the improved cooled blading system,the cooling fins 14 can be attached together by means of the common Wall16. As a result, fewer parts have to be held in an accurate relativeposition during the assembly operation.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is Itherefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specically described.

What is claimed is:

l. A turbine blade comprising a central tubular strut; a shroud; meansattaching said shroud to said strut whereby the shroud encircles thestrut and forms a space between said strut -and said shroud; a wailWithin said space disposed parallel to the strut and spaced from boththe shroud and the strut; spaced fins connecting said wall to said strutso that cooling pockets are formed adjacent the strut; means forintroducing a cooling uid into the cooling pockets dened by the wall,the ns and the stmt so that the central strut is cooled.

2. A turbine blade comprising a central tubular strut; a shroud; webmeans connecting the shroud to the strut in spaced relation thereto;U-shaped members attached to the strut in the space dened by the shroudand the strut, said U-shaped members having their bases disposedsubstantially parallel to the strut and spaced hom both the shroud andthe strut; and means to pass a cooling uid through the ibight of saidU-shaped members so that the central strut is cooled.

References Cited in the le of this patent UNITED STATES PATENTS2,369,795 Planiol Feb. 20, 1945 2,506,581 Cowles May 9, 1950 2,568,726Franz Sept. 25, 1951 2,648,520 Schmitt Aug. 11, 1953 2,708,564 EricksonMay 17, 1955 2,742,274 Lachmann Apr. 17, 1956 OTHER REFERENCES 625,693Great Britain July 1, 1949 736,800 Great Britain Sept. 14, 1955 738,213Great Britain Oct. 12, 1955 740,597 Great Britain Nov. 16, 1955

